Hi @Tom Rowland ,
First of all, thank you for your question regarding our supported Forge component, the Barcode Plugin.
Both for iOS and Android, when the user clicks the 'X' button in the scanner, the 'ScanBarcode' client action will return a value of 'False' in its the 'Success' output parameter. Furthermore, an error with code '3' will be returned in this case, which can be accessed in the 'ErrorCode' output parameter of the client action . Would checking these parameters to see if the scan was successful or cancelled help?
Let us know if this helped.
Best regards,
Alexandre Jacinto